House electric



June 12, 1928. 1,673,593

S. L. SANDERSON RADIO RECEIVING SYSTEM Filed July 1, 1924 Fly. 1.

- INVENTOR WITNESSES:

v I She/don L.6anderson.

ATTORNEY Patented June 12, 1928.

UNITED STATES PATENT OFFICE. I

SHELDON L. SANDERSON, F WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

RADIO RECEIVING SYSTEM.

Application filed July 1,

My invention relates to radio receiving systems and particularly toVernier tuning devices therefor.

One object of my invention is to provide a radio receiving system thatis suitable for the reception of a plurality of groups of wave lengths.

Another object of my invention is to produce vernier tuning means incombination with a radio receiving system.

Another object of my invention is to produce a radio receiving systemhaving a single inductive tuning device and a plurality of capacitivetuning devices that are adapted to vernier adjustment.

In the prior art of the reception of radio signals, it has been foundconvenient to construct a radio receiving system comprising an aerial, aseries condenser, a variometer, a ground connection and a detector. Ithas also been common to use a plurality of series condensive meansconnected for alternative use according to the wave length which it isdesired to receive. In the prior art, the plurality of series condensershave frequently been made each of a fixed value, leaving the tuningentirely to movement of the variometer and to choice of a larger orsmaller series condenser.

hly invention comprises means whereby a plurality of series condensersmay be used with a single inductive tuning means and, in additionthereto, means whereby a Vernier condenser is provided which isoperative with either of the series condensers- Other objects andstructural details of my invention will be apparent from the followingdescription when read in connection with the accompanying drawingwherein:

Figure 1 is a diagrammatic view of a radio receiving apparatus andcircuits according to my invention, and

Fig.2 is a plan view of a radio receiving apparatus constructedaccording to my invention.

In Fig. 1 a radio system comprises an aerial 1, a ground connection 2, atuning variometer 3, and fixed inductances 1 and 5 in series between theaerial 1 and the ground 2. To one terminal of the variometer 3 areconnected one terminal each of two conden sers 6 and 7, the otherterminals of which are connected to the binding posts 8 and 9 that are;adapted to be connected to the aerial 1924. Serial No. 723,475.

1 by a lead-in wire 11. An adjustable vernier condenser 12 is connectedbetween the binding posts 8 and 9.

The receiving apparatus contains, in addition, a triode 14, the filamentcircuit of which contains a rheostat 15, the grid circuit of whichcontains a grid leak and grid condenser assembly 16 and the platecircuit of which contains a feedback variometer 17. There are furthersupplied the customary A battery A, B battery B and the customarytelephones T.

Referring to Fig 2, a tuner control 20 is provided for the variometer 3.Another control 21 is provided for the plate variometer 17, a control 22for the rheostat 15 and a Vernier control 23 for the Vernier condenser12. Triode 14 is placed beside rheostat control 22, and the circuits areplaced within the container.

In the operation of my device, the aerial 1 may be connectedby thelead-in wire 11 to the binding post 8. The receptor circuit thencomprises the aerial 1, the lead-in wire 11, the binding post 8, thecondenser 6, the tuning variometer 3, the fixed inductances 5 and 4t andthe ground connection 2. Rough tuning may then be efiected by adjustmentof the variometer 3. The condenser 6 is shunted by condensers 7 and 12in series, condenser 7 being substantially larger than condenser 12.

By this connection, the total capacitance, in series between the aerial1 and ground and in series with the inductance 3, is fixed by the valueof the condenser 6, plus the reciprocal of the sum of the reciprocals ofthe values of the capacitance in the condensers 7 and 12. Adjustment ofthe condenser 12 thereby varies the total capacitance in the circuit andeffects very accurate tuning of the circuit of the incoming signals. Thecondenser 12 being small, a considerable movement of its dial isrequired to produce a measurable change in total capacity and noticeableeffect upon the tuning of the receptor circuit.

When it is further desired to receive a diiferent wave length, thelead-in wire 11 may be transferred from the binding post 8 to thebinding post 9, whereupon the capacitance 7 becomes the main seriescondenser and, this being of different value than the capacitance 6, thecircuit can be made resonant to a different group of radio frequenciesthan that to Wlllllll'f was resonant when the condenser 6 was the mainseries condenser. As before, rough tuning to the newly desired frequencymaybe accomplished by the -variometer 3. The total series capacitancethen becomes equal to the capacitance of the condenser 7 plus thereciprocal of the sum of the reciprocals of the capacitance of thecondenser 12 and the condenser 6. Again, the value of the total seriescapacitance is subject to a slight adjustment by a considerable movementof v the condenser 12.

By the addition of the Vernier condenser,

before described, my invention makes it possibleto produce a radioreceiving system having several series condensers that may be connected,atthe will of the operator, for the reception of different groups ofradio frequency signals, and a venier condenser co-operatin'g therewith,which gives f ne,

- of my'invention in the accompanying draw: in'gsfit is capable ofvarious mod ficatlons and changes Without departing from the spiritthereof and it is desired, therefore,

that only such limitations shall be imposed thereon as are indicated inthe prior art or in the appended claims.

I; claim as my nvention: M 1. In radio receiving apparatus, an 1n--ductor adapted to be connected to groun.d,:

a network comprising a plurality of fixed condensers oi dissimilarcapacities shunted by a variable condenser, a connection from. saidinductor to a point intermediate said fixed condensers, and meanswhereby a radiant-energy collecting device may be at will connected toeither plate of said variable condenser,whereby the system is effectiveover a plurality of wave-length ranges.

2.111 radio receiving apparatus, a variable inductor adapted to beconnected to ground, a network comprising a pair of fixed condensers ofdissimilar capacities shunted by a variable condenser having a capacityless than that of either of the fixed condensers, a connection from saidinductor to a point intermediate said fixed condensers and means for atwill connecting a radiant energy receiving device to either plate ofsaid'i ar'iable condenser, whereby the system may be rendered'receptlveover a plurality of wave-length ranges by changing the connection of theenergy receptor to saidvariable condenser. 1

In testimony whereof, I have hereunto subscribed niy namethis 23rd dayof June SHELDON L. SANDERSGN'.

